IMS LTI tool provider emulator

This is a very simple emulator of an IMS Learning Tools Interoperability (LTI) 1.1.1 tool provider (TP, e.g. a learning application
or premium content) capable of receiving launch requests from a tool consumer (TC). It includes support for the LTI 1.1 Basic Outcomes service (Outcomes 1) and the
unofficial extensions for memberships, outcomes and setting services. The Tool Settings service (defined in LTI 2.0), Outcomes 2 services, and
the Content-Item message are also supported. The shared secret is assumed to be "secret" (or the value of the custom parameter named "secret" if passed).